Once purchased the Audible is yours to keep it doesn't get removed once the loan expires. I always buy from my PC.

I had a weird thing happen last night on a library book for Kindle on the KFHD, it came with a 9 minute audible version of the book. Really weird, it was a Debbie Macomber book that she "updated" and changed the name, so there was a Ebook with the new name, and an audible with the old name with the mini audible.